(1) Field of the Invention
The present invention relates to a water pump used for supplying a coolant to cool, for example, an internal combustion engine to an inside of the internal combustion engine.
(2) Description of Related Art
A Japanese Patent Application First Publication No. 2002-349481 published on Dec. 4, 2002 which corresponds to a U.S. Pat. No. 6,764,278 issued on Jul. 20, 2004 exemplifies a previously proposed water pump. This previously proposed water pump includes: a pump housing having a pump chamber at an inner part thereof; a drive shaft made of a synthetic resin rotatably supported within the pump housing; a pulley made of the synthetic resin material rotatably supported within the pump housing; a pulley made of the synthetic resin material and integrally united to one end section of the drive shaft via a flange wall; a ball bearing installed via a cylindrical metallic insert on an inner peripheral side of the pulley; an impeller integrally rotatably installed on the other end section of the drive shaft; and a mechanical seal interposed between the impeller and the pulley.